The purpose of the proposed research is to investigate the interactions that take place at the tooth surface and which lead to the formation of the acquired enamel pellicle. This thin film of selectivity adsorbed salivary proteins covers the dental enamel surface and contains the sites to which plaque-forming organisms become attached. It therefore plays an important role in the initial stages of the formation of the dental plaque, and becomes interposed between the plaque and the underlying enamel. Since it acts as a diffusion barrier, it affects both the intensity of carious attack, and the rate of loss of the products of demineralization. The research objectives are to identify the salivary precursors of the pellicle, to study its mechanism of formation, and to identify the active sites to which the bacteria become attached. BIBLIOGRAPHIC REFERENCES: Hay, D.I. (1975) Fractionation of human parotid salivary proteins and the isolation of a histidine-rich acidic peptide which has high affinity for hydroxyapatite surfaces. Arch. Oral Biol. 20. 553-558.